The present invention relates to a process and apparatus for treating produce by-products, and particularly tomato peel material after removal of the peels from tomatoes, for the purpose of adjusting the pH level thereof to enable subsequent use of the tomato peel material in food products or to enable easier disposal of the tomato peel material.
In automated tomato processing facilities, it is common to process tomato peels after removal from tomatoes by adding acid, such as HCL acid, to the tomato peels and then adding the acidified tomato peel material to a product such as pizza sauce. Tomatoes typically have a pH level of about 4.0, but tomato peel material can have a pH level as high as 13.0 pH when the peels are removed using a caustic peeling process. It is desirable and necessary, therefore, to lower the pH level closer to approximately the 4.0 pH level of whole tomatoes, so that the peel material is suitable for use in pizza sauces and other commercial food products. Alternatively, if the tomato peel material is simply going to be disposed of, it is desirable to lower the pH level to between 8.0 and 9.0 prior to disposal.
One process for acidifying tomato peels is to introduce batches of tomato peels into an acidification tank, add acid to the peel material, circulate the tomato peels and acid in the acidification tank in order to mix the two, and then test the pH of the peel material. If the pH needs adjusting, the appropriate acid level adjustment is made and the material is mixed until the pH level is correct. When the pH level is within an acceptable range, the material is pumped out of the tank and a new batch of tomato peel material is then introduced into the tank to be acidified.
Such prior art batch systems have several drawbacks, one of which is inconsistent mixing of the pureed tomato peel material and the acid, and another of which is a slower than desired processing rate. Full, uniform mixing of the peel material and the acid is not always achieved due to the limited extent to which the acidification tank mixing system can fully mix pureed material and acid. In addition, the batch system is inherently slow because the next batch of tomato peel material cannot be acidified until acid level of the current batch is raised to the desired level. Moreover, in some instances, or as a part of the pH adjustment process, it may be necessary to raise the pH level of the tomato peel material by adding a base-containing material to achieve the desired pH level. The apparatus and process of the present invention seek to address these problems and to provide a continuous system that achieves a quick, uniform pH level adjustment of the treated tomato peel material.
The process of adjusting or controlling the pH level of tomato peel material of the present invention is comprised, briefly, of the steps of mixing tomato peel material in a receiving tank; pumping the tomato peel material from the receiving tank to a storage holding tank or to processing equipment through a mixing conduit; sensing the pH level before pumping and after pumping in the mixing conduit, and adding acid before pumping and/or in the mixing conduit, if the pH level is above predetermined levels at either pH sensing location. The mixing of added acid with tomato peel material occurs in both the receiving tank and the mixing conduit to the storage holding tank or processing equipment. The process can further include the steps of diverting tomato peel material back to the receiving tank, or to drain, from the mixing conduit, and/or adding base material to the tomato peel material if the pH level is too low.
In another aspect of the process of the present invention, a plurality of batch receiving and mixing tanks are provided and are coupled by pumps and mixing conduits to a holding tank for the processed tomato peel material. The additional receiving tanks and mixing conduits are each provided with pH sensors, and acid and/or base can be added to the tomato peel material in the receiving tanks and the mixing conduits. The input of tomato peel material from a supply source to the plurality of receiving tanks may be continuous as one tank is filled after the other, while the output pumps from the tanks are controlled to pump mixed acid and peel material from one tank while the others are being filled.
The apparatus of the present invention comprises, briefly, at least one receiving tank, a mixing device in the receiving tank, a holding tank or tomato peel material processing system, a mixing conduit between the receiving and holding tank or processing system, a pump coupled to pump tomato peel material from the receiving tank to the holding tank or processing system, pH sensors positioned to sense the pH level in the receiving tank and in the mixing conduit, an acid adding assembly coupled to add acid to the receiving tank and to the mixing conduit, and a controller responsive to pH level and level control signals to control pumping and the addition of acid to the peel material in the receiving tank, or in the transfer conduit, if the pH level sensed is above a predetermined level at one of the sensor locations. A plurality of receiving tanks enabling continuous input from a supply source or tank. A system for adding a base-containing material in response to pH level sensing signals also is optionally provided for further control capability.
These and other features, objects and advantages of the present invention will become apparent from the following description of the Best Mode for Carrying Out the Invention, when read in conjunction with the accompanying drawings, and the claims, which are incorporated herein as part of the disclosure of the invention.